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Chapter 1 -  Introduction

To overcome environmental degradation and maintain hygiene in railway premises, Indian Railway in association with DRDO (DRDE/Gwalior) has developed IR-DRDO Bio-toilets. Bio-digester filled with ‘anaerobic bacteria’ converts human waste into liquid and gases. The gases escape to the atmosphere and treated wastewater is discharged after chlorination.

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The residual water from Bio-Toilet

  • It is colorless, odorless, and devoid of any solid particles.

  • Requires no further treatment/waste management.

  • It can be used for irrigation purposes

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IR-DRDO Bio-toilet system has the following advantages:

  •  Completely environment & user-friendly.

  • Elimination of toilet discharge on stations, railway tracks, and coaching depots.

  • Improvement in the cleanliness level of the station area.

  • Improve the working environment of coaching depots & improved working conditions for maintenance staff.

  • Reduced corrosion of rails and rails fittings.

  • Eliminates load on the existing sewerage system.

  • Virtually maintenance-free.

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1.1 Green toilet aims at - Zero-Defecation on the ground

Discharge on track, besides creating environmental issues along with manual scavenging is problematic for workmen. A multi-directional strategy has been implemented for the adoption of Environment-friendly toilets on IR passenger coaches. An MOU was signed with DRDO for joint technology development. The first prototype rake with bio-toilets based on the designs developed jointly with DRDO is running successfully in Bundelkhand express since 18th January 2011. Indian Railways have decided that all coaches should be converted to work with bio-toilet by December 2018.

1.2 Working of Biological Toilet System (Anaerobic)

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Note:  System does not require oxygen and also does not require regular cleaning

1.3 Degradation process of Bacteria

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1.3.1 Aerobic Bacteria

  • Growth rate of aerobic bacteria is relatively higher

  • Requires forced aeration and large surface area

  • Large amount of bio-mass is generated

  • Disposal of bio-mass is again an environmental problem

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1.3.2 Anaerobic bacteria

  • Can process doubling its population within 6 to 8 hrs

  • Dominates and de-composes matter into liquid and gases.

  • Can be kept for 3-4 months at ambient temperature in bio-digester tank

  • Can withstand subzero temperature as well as up to 60 0 C.

  • Cold temperature would not affect the inside processing because anaerobic process is exothermic in nature & thus in cold regions, heat will be available inside the chamber because of chemical process.

 

Advantage of Anaerobic bio-toilet:

  • Require less maintenance 

  • Simple in design

  • Easier Retro fitment on existing coaches in service

  • Can be in operation up to years together

  • No oxygen and sunlight required for processing.

1.4 Advantage of IR-DRDO Bio-Digester over Conventional Toilet system: -​

  • No bad smell in toilets from the tanks

  • No infestation of Cockroaches & flies

  • Faecal matter in the tank not visible

  • No clogging of digester

  • Effluent is free from odour and solid waste

  • No maintenance required

  • Reduction in organic matter by 90%

  • No requirement of repeated adding bacteria/ enzyme

  • No need of removal of solid waste

2.0 Adoption of Bio-toilet in India Railway

First bio-digester was put in operation on coach No. NCR-05207/A of the train 1123/1124 from date of 23.08.2006.

An MOU was signed between DRDO and Indian Railway on 29.03.10 regarding joint technology development using ‘DRDE Bio-digester’ for IR toilet system and formation of joint working group(JWG) consisting of officers from Indian railways and DRDO.

The purpose of working group was the implementation of the technology development in terms of provisions of the MOU.

3.0 General Information of Bio-tank

3.1 IR-DRDO Bio-digester Tank for ICF/RCF Coaches

These tanks are made of stainless steel and having following constructional features

The size of the tank is 540 X 1150 X 720 mm with the provision of 04 nos mounting brackets at both the sides along the length of the tank. Each bracket is with the provision of 02 nos. M16 Size bolts which are tightened on mounting brackets provided on under frame.

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Main parts of the Bio digester tank:                  

  1. Stainless steel bio digester tank with 06 partitions inside the tank

  2. Colonising mats of poly grass for generation and growth of bacteria inside the bio digester tank.

  3. P-trap or S-trap for connection of toilet pan to the bio digester.

  4. SS fasteners on tank covers.

  5. SS wire meshing for protection of Colonized rubber mats with vertical walls.

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Important Dimensions & Volume of Bio-digester Tank:

1. Length - 1150 mm

2.  Width -   720 mm          

3. Height – 540 mm

4. Total Volume of Tank – 450 ltr.

5. Effective Volume of Tank–Approx. 300 ltr.

6. Empty Tank weight – 110 Kg.

7. Full Tank Weight – 410 Kg.

8.   Height from Rail level - 220 mm

3.2 Other components of Bio-Digester Tank

  1. Mounting Bracket                             -           04 Nos

  2. Safety Rope                                       -           04 Nos

  3. Locking Plate                                     -           08 Nos

  4. Hex. Head Bolt (M16 X70)               -           16 Nos

  5. Hex. Nut (M16)                                  -           16 Nos

  6. Spring Washer (B16)                        -           16 Nos

  7. Hex. Head Bolt (M8 X35)                 -           16 Nos

  8. ‘U’ Bracket (8 X20 X38)                     -           08 Nos

3.3 3D model of Bio-Digester Tank

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Partitions

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3.4 IR-DRDO Bio-digester Tank for LHB Coaches

These tanks are made of stainless steel and having following constructional features

The size of the tank is 547 X 580 X 1680 MM (HXWXL) with the provision of 02 no’s inbuilt C-Type mounting system along the length of the tank. Each mounting is with the provision of 02 nos. M16 Size bolts which are tightened with the inner and outer head stocks.

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Main parts of the Bio digester tank:

  1.  Stainless steel bio digester tank with 07 partition walls inside the tank

  2. Colonising mats of poly grass mats for generation and growth of bacteria     inside the bio digester tank.

  3. P-trap or S-trap for connection of toilet pan to the bio digester.

  4.  SS fasteners on tank covers.

  5. SS wire meshing for protection of Colonized rubber mats with vertical walls.

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3.4 Important Dimensions & Volume of Bio-digester Tank:

1. Length - 1680 mm

2. Width -   580 mm

3. Height – 547 mm

4. Total Volume of Tank - 600 liters.

5. Effective Volume of Tank – 450 liters.

6. Empty Tank weight – 120 Kg.

7. Full Tank Weight – 425 Kg.

8. Height from Rail level -225 mm.

Page Last Updated : 28/03/2023 , 17:00 , Version 1.0

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